THPDFHeadlessComparisonReport
Declared in HPDFHeadlessCompare; Mode records the selected comparison and ComparisonComplete becomes true only after successful completion
BeforePages and AfterPages record page counts; BeforeObjects and AfterObjects are populated by object-count, structural and full modes
Identical is true when Changes is empty; WorkUnits, StreamBytes and TotalPixels report the consumed traversal work, decoded structural stream bytes and rendered input pixels
THPDFHeadlessComparisonChange
Each change contains Kind, Path and PageIndex; document-wide changes use page -1, and structure uses the path $Document
Possible kinds are pageCount, objectCount, structure, page, pageText and renderedImage
Text changes include BeforeText and AfterText; rendered changes include BeforeWidth, BeforeHeight, AfterWidth and AfterHeight
PixelCount is the union canvas area, ChangedPixels counts pixels above the colour tolerance, MaxDelta is the largest channel difference, and MeanAbsoluteError averages absolute sample errors across the canvas
Similarity is 1 - MeanAbsoluteError / 255; ChangedPixelRatio is ChangedPixels / PixelCount